Student with autism, I need help

I'm student teaching right now in a kindergarten classroom where there is one student with moderate autism. He has formed a great relationship with my teacher and has little to no problems. With me, however, it's a different story and it's not only affecting him at school but also at home. Together we've decided on already having him start to meet his first grade teacher, and everyone agrees that in the long run this transition is good for him, but I still feel awful and incompetent.

Some times he won't do the work and will just shut down. We've been working on using computer time as a reward, and that sometimes works. But his volume level has increased, his emotional instability has increased, and altogether it's a constant struggle. Last week, he had a melt down because my mentor had to switch him off the computer. He came back to the classroom and laid on the floor and never having seen it before, I told him to either pick a chair or the couch in the corner to calm himself down. He went to the couch and started screaming. All the classrooms heard and I had him doing a full meltdown for ten minutes with two aides and myself coming in to try and help unsuccessfully. I know now that I should'v just left him on the floor, but that just was the turning point for behavior.

To add to it, our younger aide is not helping me, but making it harder on me because I think she's overstepping her bounds slightly. I only have her once or twice a week though, and the rest of the time its the older aide who I think does a fantastic job.

How can I help this student? Sometimes he won't listen, and I can't constantly redirect him. Other times he's too loud, but I'd rather have him loud and participating than quiet and doing no work. It's such a hard balancing act. I'm full-time teaching for 3 more weeks and I'm not honestly sure I can handle this for that long. Sometimes on carpet he'll just get up and flop around, and if I move him, he'll spin on the chair, and if it's the desk, he's not listening. It's such a hard transition for it, and I feel so bad that it's affecting him so much. Him sitting next to me helps too, but only for a really minimal amount of time.

What can I do so that both he and I survive these next few weeks? Please help, I'm desperate. I also need to start recording lessons soon and, as bad as this sounds, I want to have this somewhat figured out before that time comes.

It takes time to develop trust with any student, particularly a student with autism. Has the classroom teacher spoken to him and asked him to 'behave'?
Is the classroom teacher willing to intervene and help with behavior management so you can continue your lesson with the rest of the class?

Does the student have a full-aide aide? Can you push to have the older aide work with the student the entire time? Sometimes, the aide makes a huge difference. I had an autistic student who was very difficult and distracting. The parents were aware of this. They pushed to have a different aide. It worked. And the new aide was a LOT more successful with this student. Same student, different outcome. Something to consider.

Is the principal aware of the situation?

Working with autistic students can be challenging and there is no quick fix. You need to get all the help you can from other adults.